A phospho-driven partner switch dictates heterocyst fate in the cyanobacterium Anabaena sp. PCC 7120

Bacterial two-hybrid and co-purification assays demonstrated that NfsS binds the developmental sigma factors SigC and SigE. Deletion of the nfsR or nfsP genes abolished heterocyst formation and prevented diazotrophic growth. Comparative RNA-seq of the ΔnfsR mutant and wild type revealed downregulation of heterocyst genes in the mutant.

These included the nifHDK nitrogenase subunits encoding genes and the ferredoxin fdxH, consistent with the inability to sustain diazotrophic growth. Our findings establish a phosphorylation-dependent checkpoint that activates heterocyst-specific genes, thereby expanding the functional repertoire of partner-switch mechanisms from stress survival to programmed terminal cell differentiation. This SuperSeries contains the raw RNA-seq reads and processed count data from the wild-type and ΔnfsR mutant strains used in this study.